Ortho-diphenylphosphinobenzoic acid production

ABSTRACT

Ortho-dihydrocarbylphosphinobenzoic acids are produced in high yield substantially free of the corresponding meta-isomer by substantially immediate intimate contacting of sodium dihydrocarbyl phosphide and phenyl sodium with an orthochlorobenzoate in an inert solvent solution to produce the sodium salt of o-dihydrocarbylphosphinobenzoic acid, which is thereafter converted to the free acid by treatment with mineral acid.

United States Patent 1 Mason et al.

[ Sept. 11, 1973 ORTHO-DIPHENYLPHOSPHINOBENZOIC AClD PRODUCTION [73] Assignee: Shell Oil Company, Houston, Tex.

[22] Filed: Jan. 13, 1972 [21] Appl. No.: 217,635

[52] US. Cl. 260/515 M, 260/683.15 [51} Int. Cl. C07c 63/44 [58] Fieldof Search 260/515 M [56] References Cited OTHER PUBLICATIONSSchindlbau'er Monatsh. Chem. Vol. 96 3 (1965) pp.

Primary Examiner-James A. Patten Attorney-Howard W. Haworth and MartinS. Baer [57] ABSTRACT Ortho-dihydrocarbylphosphinobenzoic acids areproduced in high yield substantially free of the correspondingmeta-isomer by substantially immediate intimate contacting of sodiumdihydrocarbyl phosphide and phenyl sodium with an ortho-chlorobenzoatein an inert solvent solution to produce the sodium salt ofodihydrocarbylphosphinobenzoic acid, which is thereafter converted tothe free acid by treatment with mineral acid.

6 Claims, No Drawings ORTl-lO-DIPHENYLPHOSPHINOBENZOIC ACID PRODUCTIONBACKGROUND OF THE INVENTION l. Field of the Invention The presentinvention relates to the production ofortho-dihydrocarbylphosphinobenzoic acids which are compounds ofestablished utility in a variety of applications. Such acids,particularly diphenylphosphinobenzoic acid, are useful as chelatingagents for transition metals. Alternatively, such acids are employedwith certain transition metal salts and reducing agents to fonncatalysts which oligomerize ethylene to produce linear, alpha-olefinswhich are useful in forming conventional detergent precursors.

2. Description of the Prior Art Methods for preparingortho-dihydrocarbylphosphinobenzoic acids are known. For example,lssleib et al in Zeit. lnorg. Alleg. Chemie, 353, 197-206 (1967)disclose the synthesis of orthodiphenylphosphinobenzoic acid by reactionof preformed potassium diphenylphosphide with free 0- chlorobenzoicacidto produce the potassium salt of diphenylphosphinobenzoic acid,which is then converted to the free acid. This process is noteconomically attractive in that for each mole of salt ofdiphenylphosphinobenzoic acid formed, two moles of potassiumdiphenylphosphide are consumed with the resulting formation of one moleof diphenylphosphine. Other processes, in which the potassium or sodiumdiphenylphosphide are produced in situ by reaction of triphenylphosphinewith the alkali metal, require the destruction of phenyl sodium which isformed as a co-product. Phenyl sodium promotes the formation of themeta-isomer of diphenylphosphinobenzoic acid. Since the metaisomer isinactive as a catalyst component for the oligomerization of ethylene,its production must be considered as a loss in yield whenoligomerization catalyst precursors are desired. It would be anadvantage to develop a process for the production ofo-dihydrocarbylphosphinobenzoic acids without co-production ofappreciable amounts of the meta-isomer and with more efficientutilization of the substituted phosphine reactant.

SUMMARY OF THE lNVENTlON It has now been found that an improved methodfor the production of ortho-dihydrocarbylphosphinobenzoic acidscomprises 1) contact of a dihydrocarbylarylphosphine with metallicsodium in liquid ammonia, 2) addition to the reaction mixture of asuitable organic solvent, 3) substantially immediate, intimatecontacting of said mixture with free ortho-chlorobenzoic acid, and 4)conversion of the thus formed sodium orthodihydrocarbylphosphinobenzoateto ortho-dihydrocarbylphosphinobenzoic acid. The acid is then recoveredfrom the reaction mixture by conventional techniques, e.g.,crystallization from a methanol solution. The reaction mixture whereinsodium dihydrocarbylphosphide is rapidly and intimately contacted withochlorobenzoic acid results in essentially 100 percent ortho-isomer asthe reaction product. The process of the instant invention also providesfor more efficient use of substituted phosphine reactant in that onlyone mole of the phosphine reactant is required for each mole ofo-dihydrocarbylphosphinobenzoic acid formed.

DESCRlPTlON OF THE PREFERRED EMBODIMENTS Theo-dihydrocarbylphosphinobenzoic acids of this invention generally havefrom eight to 30 carbon atoms, but preferably from 14 to 20 carbonatoms, and are represented by the formula I:

wherein R independently is a monovalent hydrocarbyl group free fromnon-aromatic unsaturation, at least one R being aromatic. lllustrativeof suitable R groups are hydrocarbon alkyl R groups such as methyl,ethyl, isobutyl, lauryl, stearyl, cyclohexyl and cyclopentyl; and aryl(including alkaryl) R groups such as phenyl, tolyl, xylyl andp-ethyl-phenyl. Preferred R groups are aromatic groups of six to 10carbon atoms, especially phenyl, and cycloalkyl groups of five to 10carbon atoms, especially cyclohexyl. lllustrativeo-dihydrocarbylphosphinobenzoic acids of formula (I) are 0-diphenylphosphinobenzoic acid, o-(methylphenylphosphino)benzoic acid,o-(ethyltolylphosphino)benzoic acid, ando-(cyclohexylphenylphosphino)-benzoic acid.

The dihydrocarbylphosphino moiety results from reacting a trihydrocarbylphosphine, where the additional hydrocarbyl substituent is aryl, e.g.,phenyl, with sodium dissolved in liquid ammonia. The reaction results inthe cleavage of an aryl group from the trihydrocarbylphosphine accordingto the following reaction:

wherein 4a is a monovalent aryl group of from six to 10 carbons and Rhas the previously stated significance.

The resulting sodium dihydrocarbylphosphide is conventionally reactedwith o-chlorobenzoic acid (after first destroying the phenyl sodium byaddition of ammonium halide) to produce the desireddihydrocarbylphosphinobenzoic acid according to the following equation:

Such a process is unnecessarily wasteful of the dihydrocarbylphosphideanion.

By the process of the instant invention it has been found unnecessary todestroy the phenyl sodium prior to addition of the o-chlorobenzoic acidto the reaction mixture. Indeed, contacting the acid with the sodiumdihydrocarbylphosphide/phenyl sodium mixture results in a more efficientuse of the dihydrocarbylphosphide anion.

Thus, only one mole of sodium dihydrocarbylphosphide is required foreach mole of o-dihydrocarbylphosphinobenzoic acid produced, whereasmethods known in the art have required two moles per mole of acidreactant.

it is imperative that there be substantially immediate and intimatecontacting of the o-chlorobenzoic acid with the reaction mixturecontaining both the dihydrocarbylphosphide anion and the phenyl sodium.If the addition of the acid occurs over an extended interval of time,there is produced a mixture of orthoand meta-isomers of thecorresponding dihydrocarbylphosphinobenzoic acid, typically with as muchas up to 35 percent meta isomer. With the substantially immediatecontacting of reactants, the selectivity to the ortho isomer approaches100 percent.

PROCESS CONDITIONS In the process of the instant invention alloperations must be performed under an inert gas blanket because of thereactivity of the reactants and intermediates formed toward theatmosphere. The reaction vessel should also be inert to the reactionenvironment;.therefore, glass is a preferred material of construction.The reaction vessel, in addition to providing an inert environment inwhich to contact the reactants, should be equipped with a means forinsuring adequate reactant contacting and adequate temperature control.

The first step of the synthesis requires that metallic sodium bedissolved in liquid ammonia. The sodium is added slowly to liquidammonia in the reactor under constant agitation. The resulting mixturewill exhibit an intensely blue color. The amount of liquid ammonia usedis not critical and can vary widely. Typically up to two liters ofammonia per mole of sodium to be dissolved is satisfactory. This mixtureis kept substantially in the liquid phase by cooling.

After the sodium is completely dissolved in the liquid ammonia,approximately one mole of the aryl dihydrocarbylphosphine, e.g., fromabout 0.25 mole to about 0.75 mole is then added to the mixture for eachmole of sodium charged to the reactor. Since the reaction of the aryldihydrocarbylphosphine with metallic sodium is quite exothermic, theaddition is typically performed slowly with cooling so as to maintainthe mixture substantially in the liquid phase.

After the addition of the sodium is completed, a suitable misciblesolvent, e.g., dioxane, is added to the sodiumdip'henylphosphide-ammonia mixture. Suitable solvents or diluents arepolar organic compounds liquid at reaction temperatures in which boththe sodium dihydrocarbylphosphide and o-chlorobenzoic acid are soluble.Amounts of solvent of up to 2 liters per mole of sodiumdihydrocarbylphosphide are satisfactorily employed at this stage of thesynthesis. However, additional solvent is generally added to thereaction mixture as the o-chlorobenzoic acid is generally added as asolution in the same solvent. The total reaction mixture typicallycontains up to 5 liters of solvent 'per mole of acid produced.

Illustrative of suitable solvents are polar organic compounds such asorganic compounds containing atoms such as oxygen, sulfur and phosphorusincorporated in functional groups, not containing active hydrogen, suchas alkoxy, aryloxy, carbalkoxy, alkanoyloxy, and like functional groups.Illustrative oxygenated organic solvents are fully esteritied polyacylesters of polyhydroxy alkanes such as glycerol triacetate; tetraacrylesters of erythritol; diethylene glycol diacetate; cycloalkyl ethers,e.g., dioxane, tetrahydrofuran and tetrahydropyran; acyclic alkylethers, e.g., dimethoxyethane, diethyleneglycol dimethyl ether anddibutyl ether; aromatic ethers such as anisole, 1,4- dimethoxybenzeneand p-methoxytoluene; and alkylene carbonates such as ethylenecarbonate, propylene carbonate and butylene carbonate. illustrativesulfurcontaining solvents are sulfolane and dimethylsulfoxide andillustrative phosphorus-containing solvents are trialkylphosphates,e.g., trimethylphosphate, triethylphosphate and tributylphosphate andhexaalkylphosphoramides such as hexamethylphosphoramide.

Preferred reaction solvents are oxygenated organic solvents,particularly the ethers. Especially preferred are cycloalkyl ethers,e.g., dioxane and tetrahydrofuran, and acyclic alkyl ethers, e.g.,diglyme (diethylene glycol dimethyl ether).

After the addition of solvent to the reaction vessel is complete, theortho-chlorobenzoic acid in a suitable solvent as defined above is addedto the reaction vessel. From about 0.5 mole to about 2 moles ofochlorobenzoic acid per mole of the phosphine previously added isemployed. Any time lapse between addition of the solvent and subsequentaddition of substituted benzoic acid is not material, however, it isimportant that once addition of the benzoic acid is initiated, there besubstantially immediate intimate contacting of the benzoic acid and thesodium diphenylphosphidelphenyl sodium mixture. The faster the additionrate of the acid, the higher will be the yield of the orthoisomer. Whenall of the acid has been added to the reaction vessel, the reactiontemperature is then gradually increased and the mixture is maintainedunder agitation until reaction of the o-chlorobenzoic acid is complete.

The final step in the process is acidification of the hot solution witha strong mineralacid, e.g., hydrochloric, to thereby recover theorthodihydrocarbylphosphinobenzoic acid. it is generally advantageous,although not required, to add water and remove the organic solvent priorto acidification. After acidification the aqueous phase is removed andthe solid product is then recovered by conventional techniques, e.g.,washing, separating, and drying.

The process of this invention'is used in the production ofortho-dihydrocarbylphosphinobenzoic acids, useful, for example, as acatalyst component in the oligomerization of ethylene to producelong-chain, linear, alpha-olefins which are useful in the production ofdetergents.

To further illustrate the process of the invention, the followingexamples are provided. It should be understood that the details thereofare not to be regarded as limitations.

lLLUSTRATlVE EMBODIM ENT l A. To a 3 liter 3-necked flask equipped witha glass 5 The data are summarized in the following Table l.

V '7 TABLE I Diphenylphosphine- Reactor conditions benzoic acid isomerO-chlorobenzoic distribution acid addition Temp., Time, Percent M .1.time C. hrs. yield C. Ortho Meta Minutes:

liquid ammonia solution was added 23 g. (1.0 gram atom) of sodium whichhad been freed of protective oil by washing with pentane and drying in astream of nitrogen. The sodium was added in portions over a period of 15minutes and the resulting intensely blue solution was stirred for anadditional 15 minutes.

To this mixture 131 g. (0.5 mole) of triphenylphosphine was added slowlyso as to maintain a gentle reflux. The reaction was quite exothermic and30-40 minutes was required to complete the addition. The resulting darkred solution was then stirred for 90 minutes. A solution ofo-chlorobenzoic acid 78.5 g (0.5 m) in dry tetrahydrofuran (250 ml) wasadded over a period of 53 seconds. More tetrahydrofuran solvent (1400ml) was added and the contents of the flask were then heated to removethe ammonia. When the internal temperature reached 10C the condensercoolant was switched to water and the mixture was heated under reflux(initial temperature 67C) for 22 hours. During this period the reactionmixture passes through a viscous, difficultly stirrable phase. As thereaction progresses the viscosity decreases and stirring improves.

The reaction mixture was worked up by addition of hot deoxygenated waterand removal of the solvent as an azeotrope (bp 87). Water was added tomaintain the liquid level. When the stillhead temperature had reached94C a total of 2.0 liters of water had been added and 1850 ml ofdistillate had been obtained. The kettle temperature was 97C. The flaskwas cooled to 80 and the aqueous mixture extracted three times with 100ml portions of perchloroethylene. Entrained chlorocarbon was removedazeotropically. The 0- diphenylphosphinobenzoic acid was obtained byaddition of 6N l-lCl to the reaction flask until no further cloudingoccurred (85 ml). The supernatant liquor was decanted and the crudeproduct washed with boiling water. After drying the product weighed 113g. (74 percent yield). Analysis of the product as to isomer distributionwas made by silylation subsequent and chromatographic analysis on a6 ftSE-30 column at 265C. The product analyzed approximately 99 percentorthodiphenylphosphinobenzoic acid. The melting point was determined tobe 175-178C.

B. The above procedure was repeated except that the o-chlorobenzoic acidwas added over a period of 85 minutes. The crude product, 117.4 g. (77percent yield) had a melting point of 135-163C and was found to contain31 percent meta- From the above data it is apparent that the yield ofthe ortho isomer is higher when the o-chlorobenzoic acid is added at amore rapid rate.

ILLUSTRATIVE EMBODIMENT II A. To a 300 ml Magnedrive autoclave wascharged 0.25 millimoles NiCl .6H,O, 0.125-025 millimoles ofo-diphenylphoshinobenzoic acid, 65 ml 1,4-butanediol and 500 psig ofethylene. After the autoclave was maintained at 25C for 15 minutes, 0.50millimoles of sodium borohydride (0.5 molar solution in N,N-dimethylacetamide) and an additional 600 psig of ethylene (totalethylene pressure 1 100 psig) were charged to the autoclave. Theautoclave was maintained at 25 C for 15 minutes and then heated to C andmaintained at a pressure of 1 psig by continual addition of ethyleneuntil ethylene uptake ceased.

The rate of ethylene oligomer formation was 490 grams oligomers per gramnickel per hour. The oligomer products consisted of 32.5 percent wC,,-C, oligomers. Gas liquid chromatographic analysis of the C fractionof the oligomers showed that the C olefins consisted of about 98 percentlinear a-olefins, about 1 percent linear internal olefins and about 1percent branched olefins.

B. For comparative purposes the procedure of part A was repeated exceptthat metadiphenylphosphinobenzoic acid was used in the catalystcomposition instead of the ortho-isomer. No oligomer products wereformed.

We claim as our invention:

1. The process of preparing ortho-dihydrocarbylphosphinobenzoic acidsubstantially free from the meta-dihydrocarbylphosphinobenzoic acidisomer which comprises,

a. contact of an aryldihydrocarbylphosphine and sodium in liquidammonia,

b. addition thereto of an inert solvent, and

c. substantially immediate, intimate contact of the mixture withortho-chlorobenzoic acid in an inert solvent solution, and recoveringortho-dihydrocarbylphosphinobenzoic acid from the reaction mixture bysubsequent treatment with mineral acid.

2. The process according to claim 1 wherein thearyl-dihydrocarbylphosphine is triphenylphosphine.

3. The process according to claim 1 wherein thearyl-dihydrocarbylphosphine is phenyldibutylphosphine.

4. The process according to claim 2 wherein the inert solvent isdiethyleneglycol dimethyl ether.

5. The process according to claim 2 wherein the inert solvent isanhydrous dioxane.

6. The process according to claim 2 wherein the inert solvent isdi-n-butyl ether.

* i t i i @3 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent No. 3 753 553 Dated September 11, 1973 Inventor) RONALD F. MASONand GORDON E. WICKER It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

F- In the Abstract, line 5 which reads "an ortho-chlorobenzoate" shouldread orthochlorobenzoic acid-;

In Column 1, lines 58 through 60, the phrase which reads "The reactionmixture wherein sodium dihydrocarbylphosphide is rapidly and intimatelycontacted" should read -Rapidly and intimately contacting the mixturecontaining sodium dihydrocarbylphosphide, and phenyl sodium--;

In Column 2, lines 53-61, the compound in the equation which reads CO HShould read CO Na In Column 3, line 3, to the sentence ending with"anion". should be added the phrase as is illustrated by the followingequation--;

Claim 3, Column 6, lines 60 through 63, should be cancelled.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3758 DatedSeptember 11 1973 Inventor) Ronald P. Mason and Gordon E. Wicker Page 2It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

On the cover sheet, after the abstract, "6 Claims" should read 5 ClaimsSigned and sealed this 19th day of Marbh 197 4.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. Q C. MARSHALL DANN Attesting Officer Commissionerof Patents FORM Po-wso (10-69) USCOMWDC 6037b";

* UTS. G'VEINHENT PRINTING OFFICE I"? O3-J3l.

2. The process according to claim 1 wherein thearyl-dihydrocarbylphosphine is triphenylphosphine.
 3. The processaccording to claim 1 wherein the aryl-dihydrocarbylphosphine isphenyldibutylphosphine.
 4. The process according to claim 2 wherein theinert solvent is diethyleneglycol dimethyl ether.
 5. The processaccording to claim 2 wherein the inert solvent is anhydrous dioxane. 6.The process according to claim 2 wherein the inert solvent is di-n-butylether.